Mechanical behavior and laboratory survival of thin and ultrathin ceramic crowns: A systematic review and meta-analysis

Abstract

Purpose

The evidence on the mechanical reliability of thin and ultrathin ceramic crowns is inconclusive. This systematic review aimed to collect all the data on thin and ultrathin ceramic crowns, assessing their fatigue survival, mechanical behavior, and optical properties within laboratory measures.

Methods

A comprehensive literature search was conducted across PubMed, Scopus, Cochrane, and Google Scholar, concluding on May 20, 2025. All relevant studies were screened for eligibility; only English-language, peer-reviewed articles containing extractable data on thin or ultrathin ceramic crowns (measuring 0.6 to 0.9 mm and ≤ 0.5 mm, respectively) were included in this review. The meta-analysis was performed using RevMan 5.4 software from the Cochrane Collaboration, with p ≤ 0.05.

Results

A total of 14 studies were included. Both thin and ultrathin crowns demonstrated durability under thermomechanical loading for 5 years during clinical simulation. The fatigue survival rates under stepwise loading presented conflicting findings, which may be attributed to variations in procedural methodologies or cementation protocols. The mechanical strength of thin and ultrathin crowns was sufficient to endure occlusal stresses exceeding 1100 N. However, the fracture resistance of thin and ultrathin crowns was found to be statistically significantly lower than that of thick ceramic crowns (p = 0.01 and p ≤ 0.001, respectively). Furthermore, all crowns cemented with conventional cement exhibited statistically significant weakness compared to those bonded with resin cement (p ≤ 0.001). Lithium disilicate and nano lithium disilicate crowns revealed more stable optical properties than zirconia-reinforced lithium silicate, and all exhibited more staining with longer exposure time to colored drinks. Resin ceramic crowns revealed the highest microleakage rate compared with zirconia and composite crowns.

Conclusions

Laboratory evidence suggests that thin and ultrathin ceramic crowns exhibit favorable survival rates and fracture resistance. Crowns fabricated from high-strength ceramics such as 3Y-TZP performed better with conventional cements, whereas crowns cemented with adhesive resin protocols yielded similar fracture resistance regardless of crown thickness or material. Optical properties and microleakage are crown-material and time-dependent; however, evidence is scarce and remains insufficient. Thin and ultrathin ceramic crowns offer a conservative treatment option. Adhesive cementation enhances their survival, while the choice of ceramic material, cementation protocol, and luting shade is critical for optimal esthetics.